Combined vacuum circuit interrupter and impedance means



COMBINED VACUUM CIRCUIT INTERRUPTER AND IMPEDANCE MEANS Filed D60. 14,

Nov. 17, 1970 2. A. WACHTA 2 Sheets-Sheet 1 z. A. WACHTA 3,53,2fi

COMBINED VACUUM CIRCUIT INTERRUPTE'R AND IMPEDANCE MEANS Filed Dec. 14,1967 2 Sheets-Sheet 2 I? w I 2 F E 1 l? 76": x V W I l Wis.

Filed Dec. 14, 1967, Ser. No. 690,597 Int. Cl. H01h 33/6'6 US. Cl.200-144 4 Claims ABSTRACT OF THE DISCLOSURE A vacuum circuit interruptercomprising a cylindrical glass envelope having a pair of axially alignedrelatively movable butt type contact rods extending thereinto isprovided with impedance means comprising a pair of cylindrical metalshields which are concentrically arranged with respect to the contactrods and each other and electrically connected to respective contactrods. In one embodiment, the shields are located within the envelope andin another embodiment, the shields are located or embedded within theenvelope wall. In a further embodiment, resistance means which alsomechanically support the shield are connected in series circuit betweeneach shield and its respective contact rod.

SUMMARY OF THE INVENTION In high voltage electrical systems which useseries connected vacuum interrupters, more equal voltage distributionbetween the interrupters can be obtained by connecting impedance means,such as a resistor or capacitor, in parallel with each vacuuminterrupter. Heretofore, this impedance means took the form of separateresistors or capacitors which were externally connected in parallel witheach of the series connected interrupters. However, this approachresulted in the extra cost of separate cornponents and mounting meansand all components were required to meet the same dielectricrequirements of the interrupters themselves.

In accordance with the present invention, there is provided aninterrupter, such as a vacuum interrupter, wherein impedance means, suchas capacitors and resistors, occupy the same space and dielectric mediumof the inter- United States Patent O rupter itself. More particularly,there is provided an interrupter having an envelope with a pair ofrelatively movable contact rods therein and a pair of concentricallyarranged cylindrical shields within the envelope or embedded in it whichsurround the contact rods and are electrically connected to respectiverods. In another embodiment of the invention, resistance means arelocated within the envelope and are connected in series with theshields.

OBJECTS It is an object of the invention to provide improved electricalcircuit interrupters which have impedance means integral therewith forequalized voltage distribution.

Another object is to provide such interrupters wherein the impedancemeans takes the form of capacitors, resistors, or a combination of both.

Another object is to provide such interrupters which comprise anenvelope in which butt type rod contacts are employed and the capacitorstake the form of tubular shields which also serve to shield against thediffusion of arc products.

Another obect is to provide an interrupter of the aforesaid characterwherein the resistance means in series with the tubular shields formpart of the supporting structure thereof.

Other objects and advantages of the invention will hereinafter appear.

DRAWINGS The accompanying drawings illustrate several preferredembodiments of the invention, but it is to be understood that theembodiments illustrated are susceptible of modifications with respect todetails thereof without departing from the scope of the appended claims.

In the drawings:

FIG. 1 is a cross sectional view of a vacuum interrupter incorporatingcapacitors and resistors in accordance with one embodiment of theinvention;

FIG. 2 is a view taken along line l'I-II of FIG. 1;

FLIG. 3 is a cross sectional view of a vacuum interrupter incorporatingcapacitors in accordance with another embodiment of the invention; and

FIG. 4 is a view taken along line IVIV of FIG. 3.

DESCRIPTION OF THE INVENTION Referring to FIG. 1 of the drawing, thenumeral 10 designates a high voltage vacuum type electrical circuitinterrupter or switch in accordance with one embodiment of the presentinvention. Switch 10 comprises an envelope 12, preferably made ofinsulating material, such as glass, which is hermetically sealed at oneend by a closure means, such as a metal cap, 14 to which a stationarybutt type electrically conductive contact rod 16 is mechanically andelectrically connected. Envelope 12 is hermetically sealed at its otherend by a closure means 1 8 to which a movable butt type electricallyconductive contact rod 20 is mechanically and electrically connected.The exterior ends of the rods 16 and 20 are understood to be adapted forconnection in an appropriate electrical circuit. Closure means 18comprises an electrically conductive ring 22 which is rigidly connectedto envelope 12, an electrically conductive collar 24 which is rigidlyconnected to ring 22, and a bellows 26 which is connected between anannular member or washer 28 on rod 20 and an annular member or washer 30in collar 24. Collar 24 is provided with an electrically conductivemounting flange 32. It is to be understood that bellows 26 permits axialmovement of rod 20 between contact closed position (shown in FIG. 1)wherein the rods 16 and "20 butt, and contact open position (not shown)wherein the rods 16 and 20 are slightly separated.

As FIGS. 1 and 2 show in accordance with the invention, switch 10 isprovided with a first electrically conductive tubular shield or member34 which is spaced apart from and surrounds the contact rods 16 and 20in coaxial relationship and serves as one plate or element of acapacitor. Means are provided to electrically and mechanically connectshield 34 to rod 20- and such means take the form of an electricallyconductive ring or member 36. In accordance with one aspect of theinvention, ring 36 could merely be made of highly conductive metal, suchas copper. However, in accordance with another aspect of the invention,ring 36 could be made of material having high electrical resistance andwould then serve as a resistor in series circuit with one side of thecapacitance means herein described. In addition to its function as acapacitor plate, shield 34 also serves to prevent the dispersion of areproducts during separation of the rods 16 and 20.

Switch '10 is further provided with a second electrically conductivetubular shield or member 38 which is spaced apart from and surrounds thefirst shield 34 in coaxial relationship and serves as another plate orelement of a capacitor. Means are provided to electrically andmechanically connect shield 38 to rod 16 and such means take the form ofan electrically conductive ring or member 40.

3 Ring 40, like ring 36, could be made of highly conductive metal, suchas copper, or could be made of high resistance material.

The shields 34 and 38, which are substantially coextensive with eachother in the embodiment shown in FIG. 1, add substantial capacitance tothe circuit when the rods 16 and 20 are energized and are in spacedapart, open circuit position. For example, the inherent capacitance ofan actual switch similar to switch (but having a single shield 34 tosuppress are products) was on the order of 3 micromicrofarads.Capacitance increased to about 40 micromicrofarads with the arrangementshown in FIG. 1. Further increases or decreases in capacitance woulddepend on the shape, spacing and area of the shields 34 and 38 and thesize and shape of the rods 16 and 20.

Referring to FIG. 3 of the drawing, the numeral 50 designates anotherhigh voltage vacuum type electrical circuit interrupter or switch inaccordance with another embodiment of the present invention. Switch 50comprises a glass envelope 52 which has closure means 54 and 58 atopposite ends which are similar to the closure means 14 and 18hereinbefore described in connection with FIG. 1. Switch 50 also hascontact rods 56 and 60 similar to the contact rods 16 and 20hereinbefore described.

As FIGS. 3 and 4 show in accordance with the present invention, switch50 comprises first and second coaxial tubular shields 74 and 78 which,for example, are similar in size, shape and function to the shields 34and 38 hereinbefore described. However, the shields 74 and 78 are Iembedded in the wall of insulating envelope 52 of switch '50 whichmechanically supports them.

The shields 74 and 78 serve as capacitance means in substantially thesame manner as the shields 34 and 38 hereinbefore described. Since theshields 74 and 78 are embedded, shield 74 is not available as acondensing shield for arc products. Accordingly, a separate condensingshield 79 is provided in switch 50.

Means are provided to electrically connect the shields 74 and 78 totheir respective rods and such means take the form of electricallyconductive extensions 76 and 80, respectively, of the shields. However,other forms of electrical conductors or resistors could be used insteadof the extensions 76 and 80.

As is apparent, switches such as 10 and 50 have the impedance meansintegral with switch structure itself rather than externally attached,and the dielectric integrity of the switch extends also to the impedancemeans. Thus, the need for separately mounted and insulated units iseliminated thereby reducing the number or; components, eliminatingadditional space requirements, andreducing costs.

The embodiments of the invention in which an exclu- 41 sive property orprivilege is claimed are defined as follows:

1. In a vacuum interrupter,

an envelope,

a pair of relatively movable contact rods extending into said envelopeand adapted to make butt' contact therein, v

' a first electrically conductive tubular capacitance mem bersurrounding portions'of both of said contact rods, first resistancemeans for electrically connecting said first member to one of saidcontact rods,

p a second electrically conductive tubular capacitance memberspacedapart from and surrounding said first member and portions of both ofsaid contact rods, said second member being substantially coextensivewith and immovable with respect to said first memb v I and secondresistance means an electrically connecting said second member to theother of said contact rods,

said first and second electrically conductive tubular capacitancemembers and said first and second resistance means cooperating toprovide impedance means in parallel with said pair of movable contactsfor voltage distribution purposes,

- 2. 'A vacuum interrupter according to claim-1 wherein said'envelope ismade of insulating material and said members are embedded in saidenvelope.

3. A vacuum interrupter according to claim 1 wherein said members arelocated within said envelope.

4. A vacuum interrupter according to claim 1 wherein said electricalresistance means provide mechanical support for the members with whichit is in series.

References Cited UNITED STATES PATENTS 2,185,719 1/ 1940, Baker 200-2,358,553 9/1944 Beldi. 3, 147,35 6 9/1964 Luehring -1 .200.-144.2 X r3,185,800 5/1965 Titus 200-1442 3,43 0,015 2/ 1969 Crouch et a1. 200'144.2 2,979,588. 4/1961 Jennings 20 0,144.2 Y FOREIGN PATENTS "693,827"9/ 1964 Canada. 975,483 12/1961 Germany.

oB-ERT s. MACON, Primary Examiner i U.S. c1. X.R.

